Warning or signal light systems are in widespread use for various applications and particularly as traffic control devices to warn of hazardous road conditions. Similarly, visual warning system for aircraft traffic control are in demand and are particularly critical in providing an adequate visual warning to pilots of the existence of a closed runway where visual warnings are necessary in addition to voice warnings from the traffic controller. In designing a warning light system for use as a runway marker, it is important that the device be readily transportable so as to be capable of being vehicle-mounted or towed by a vehicle into and out of position in a minimum of time. Further, it is desirable to enable towing of one or more marker systems at a time so that one may be positioned at each end of the runway. In the past, among other problems in effectively designing runway markers is to construct the markers large enough and bright enough to be readily visible for several miles but nevertheless be capable of being collapsed or retracted into a relatively compact size that can be readily towed around a crowded aircraft terminal.
Of the warning light systems that have been devised for traffic control, U.S. Pat. No. 4,835,515 to J. A. McDermott et al discloses a vehicle-mounted signal light system which is intended for use on emergency vehicles and consists of light bars that are pivoted at an end of a frame so that teach bar must be independently pivoted or rotated in an upward direction to a specific acute angle. U.S. Pat. No. 4,253,085 to H. T. Hidler et al proposes to mount a series of lights in perforated metal tubing members which are arranged in various configurations but is not readily transportable and not suited for use as a runway marker. U.S. Pat. No. 4,759,606 to R. A. McDowell discloses an arrangement of marker lights with a reflector assembly on light bars or struts which are joined at a common center and specifically designed for use by a vehicle driver to place near the vehicle in the case of vehicle breakdown. However, the device is designed to be stowed within the vehicle when not in use and is not conformable for mounting on a vehicle so as to be readily advanced into a position to serve as a warning light. Other U.S. Letters Patent of interest are U.S. Pat. Nos. 1,334,191 to T. G. Thomas; 1,987,863 to L. S. Murphy; 2,782,745 to W. C. Paschke; 3,487,553 to A. L. Stingl; 4,170,767 to J. H. Tanner; 4,812,844 to W. H. Kallstrom and 4,857,920 to S. Kataoka et al. To our knowledge, no one has successfully devised a runway marker system which is readily transportable in the manner described and which can be expanded to a size greatly in excess of the supporting frame or structure and tilted to the desired angle so as to be readily visible to approaching aircraft.